In the field of cosmetic, personal care, and pharmaceutical products emollients are usually defined as an agent that softens or smooths the skin and which tend to reduce the roughness, cracking and irritation of the skin. This smoothing is believed to be effected by the penetration of the emollient into the surface layers of tissue, through the slight congestion induced by rubbing and massage upon application, and especially through interference with sensible and insensible water loss. The ancient Greek physician, Galen, is thought to have made one of the first emollients consisting of beeswax, spermaceti, almond oil, borax and rosewater.
Emollients tend to be bland, fatty, oleaginous substances which may be applied locally to the skin, mucous membranes, or abraded tissue. One of the benefits of emollients is their ability to exclude water-soluble irritants, air, and air-borne bacteria when a layer of emollient is present. At the present, there are numerous ingredients which function as emollients in a wide variety of products, and which ingredients may act in subtly different ways. For example, certain emollients sit on the surface of the skin and serve to impede water loss from the skin. Such ingredients are generally comprised of large molecules that form a hydrophobic barrier to help prevent water from leaving the surface of the skin. Examples of such emollients are lanolin, mineral oil, silicone derivatives and petroleum jelly.
A chief use of emollients is to provide vehicles for lipid-soluble drugs (as in balms, ointments and alcohol-based liniments). Although it has often been suggested that such emollient vehicles facilitate the transport of such drugs through the skin, it has been found that when the oil:water partition coefficient is greater than 1.0, the penetration of lipid-soluble drugs tends to be impeded. Emollient substances are commonly employed in cleansing and antiphlogistic creams and lotions. Compound ointment bases, creams, and other medical applications are also general areas of use for emollients. Amongst the more common emollient materials are castor oil, corn oil, cottonseed oil, rose water ointment, apricot kernel oil, avocado oil, grape seed oil, hazelnut oil, olive oil, sesame oil, theobroma oil, almond oil, myristyl alcohol, and recently other natural oils such as jojoba oil.
Other ingredients that have been used as emollients include a number of fatty acids derived from either plants or animal sources. Fatty acids generally comprise aliphatic hydrocarbon or other organic chains with carboxylic substituents on them, typically having between 8 and 24 carbon atoms in the chain backbone. Fatty acids are often used in creams, lotions, shaving creams, lipsticks and as pressing agents in pressed powders and blushes. Fatty acids which are used in cosmetics formulations generally include at least stearic acid, oleic acid, myristic acid and palmitic acid. Other typical fatty acids include linoleic acid, behenic acid, and other common fatty acids of the general formula C.sub.n H.sub.2n+1 COOH.
Fatty alcohols are also used as emollients. They are said to be less sticky and less heavy than many other fatty materials, such as the fatty acids, and are frequently used to improve the viscosity and stability of lotions and creams. They also have utility in reactive hair dying and perming products. Examples of fatty alcohols which find use in the field of cosmetics and personal care products are cetyl alcohol, lauryl alcohol, stearyl alcohol and oleyl alcohol.
Additional examples of emollients are fatty esters. One of the best qualities of fatty esters is that they do not feel as oily to the touch as some other types of emollient fatty ingredients. Examples include isopropyl palmitate, isopropyl myristate and glyceryl stearate.
An important emollient is jojoba oil which is derived from the seed of the species Simmondsia chinensis. Jojoba is a seed oil with excellent skin feel. The oil is composed almost exclusively of wax esters, with little or no triglycerides present. A major portion of the production of jojoba oil is used by the cosmetic industry as an emollient in a variety of products.
The art of perfumery is an ancient skill with origins generally traced to the first Dynasty of Egypt, which was ruled by Menes sometime between 3500 and 500 BC. Sesame, almond and olive oils were used as solvents to extract the aromatics from vegetable materials and also as vehicles for delivery of the aromatics to the skin. Early Greek writers recorded the use of oils to "fix" or to retard evaporation of fragrance compounds. The early Romans showed little interest in perfumes and in fact perfumed unguents were forbidden in Rome by edict in about 188 BC. By the time Nero was Emperor in A.D. 54, the Romans had migrated into southern Italy and acquired a more intimate knowledge of the aesthetic side of life from the Greeks who occupied the area. Greeks and Romans used sesame, olive, or bean oils to extract and deliver the fragrance compounds and according to Pliny, resin and gum were added to "fix" the odor lest "it is apt to die away and disappear with the greatest rapidity if these substances are not employed." The first alcoholic perfume base appeared in 1370 and was known as "Hungary Water," a name attributed to Queen Elizabeth of Hungary who first commissioned its preparation. The use of alcoholic bases to deliver fragrance compounds to the skin became the method of choice around the world. Some Middle Eastern regions still adhere to the more traditional use of sesame or olive oils as fragrance carriers.
Modern purveyors of perfumes and perfumed cosmetics have social and legal mandates to reduce the amount of Volatile Organic Compounds (VOC's) released into the atmosphere by their products. Modem technology has also identified alcohol as an agent which dries the skin and therefore there has been a desire for "alcohol free" cosmetic and personal care products. Additional carriers and vehicles for perfumes that are acceptable to the industry and consumers are also needed.
One of the problems with typical emollients is that the emollient itself provides a wet or oily feel to the applied areas. This can lead to an uncomfortable feeling or appearance to the user, which is very important in the cosmetic and pharmacological industry. An additive for cosmetic, personal care and topical treatment (medicament) products has been marketed under the name of "Confetti".TM. (with different alphanumeric identifiers as to specific ingredients, e.g., Confetti.TM. AL with allantoin, and Confetti.TM. EA, MT, PA, RG and SG identifying the color of the material). This material is advertised as decorative microcapsules which contribute beneficial moisturizing and delivery of alcohol soluble ingredients to the skin. Confetti.TM. is advertised as having a good balance of structural integrity and rub-in characteristics, rubbing into the skin completely without any extra pressure. The Material Safety Data Sheets (MSDS) on Confetti IMproducts identifies them as containing a natural oil (e.g., coconut oil, tocopheryl acetate, retinyl palmitate), propylene glycol, synthetic beeswax, petrolatum, allantoin, PVM/MA Decadiene crosspolymer and benzophenone, as well as pigments and/or dyes.